Effects of lipotropic substances on the cholesterol content of the serum of rats.

1. Crystalline cholesterol was added at different concentrations (0.2, 0-4, 0-8 and 1-6 %) to a hypolipotropic diet. The livers of rats fed these rations and of other rats fed similar rations containing various lipotropic supplements were analysed for lipid content. 2. At moderate intakes of cholesterol (0.2 %) sufficient dietary choline or betaine were able to prevent the excessive deposition of both glycerides and cholesteryl esters. 3. In rats consuming diets rich in cholesterol, even considerable concentrations ofcholine (1-28 %) in the diet failed to prevent an excessive accumulation of cholesteryl esters in the livers. 4. In a curative experiment, betaine hydrochloride at a concentration of 0-42 % in the diet was about as active as an equimolecular amount of choline in hastening the removal of glycerides and cholesteryl esters from 'cholesterol fatty livers'. The limited data suggest that had the effect of lower dosages been compared, betaine would have been found to be less effective than choline. 5. Vitamin B12 exerted a considerable curative lipotropic action on the glycerides but much less on the cholesteryl ester fraction of liver lipids. 6. Inositol was without any appreciable lipotropic effect on either fraction in either type of study. The expenses of this study were defrayed in part by a grant from the Banting Research Foundation to the Department. Preliminary reports of this work were presented before the Division of Biochemistry of the Chemical Institute of Canada at recent Annual Conferences (Montreal, 1952; Windsor, 1953). REFERENCES